1. Field of the Invention
The present invention relates to a method for producing a stator of an alternating current dynamo-electric machine, for example, an alternating current generator for automobiles, which is driven by an automobile engine, or the like.
2. Description of the Related Art
FIG. 4 is a cross-sectional view showing an example of an alternating current generator for automobiles to which the present invention can be applied. In this figure, a rotor 1 includes a rotating shaft 11, a pair of claw pole field cores 12 mounted to the rotating shaft 11, and a field coil 13 fixed within the pair of field cores 12. The rotating shaft 11 is rotated by transmitting a driving force of an automobile engine through a belt (not shown).
A stator 2 surrounding the rotor 1 includes a stator core 21 and a stator coil assembly 22 fixed to the stator core 21. The inner peripheral surface of the stator 2 is opposed to the outer peripheral surface of the rotor 1 through a gap. The stator 2 is held in place between a front bracket 3 and a rear bracket 4. Furthermore, the rotor 1 is supported by the front bracket 3 and the rear bracket 4 through bearings 31 and 41 respectively.
A conventional method for producing the stator 2 will now be described in conjunction with FIG. 5. First, a strip 20 having a plurality of slots is cut from a long, narrow steel plate as shown in FIG. 5. At this time, two strips 20 can be cut from one steel plate. Next, one strip 20 is wound into a ring to produce the stator core 21 having a prescribed semi-diameter as shown in FIG. 6. A plurality of slots 21a are provided on the inner peripheral surface of the stator core 21.
On the other hand, the stator coil assembly 22 is formed into a cylindrical shape as shown in FIG. 7. The cylindrical stator coil assembly 22 is brought into the inside of the cylindrical stator core 21 along a guide (not shown) by an assembling apparatus (not shown) while bending its end portion, and thereafter inserted into the slots 21a of the stator core 21 to obtain the stator 2 as shown in FIG. 8.
Further, methods disclosed, for example, in U.S. Pat. No. 416,033 and Japanese Patent Laid-Open No. 52-34301 are known as methods for producing the cylindrical stator core 21.
In the conventional method for producing the stator 2 as described above, the stator coil assembly 22 is inserted into the slots 21a after being pre-formed into the cylindrical shape so as to correspond to slots 21a disposed cylindrically. This assembly operation is complicated and the stator coil assembly 22 is sometimes damaged. Therefore, a production efficiency is reduced. Further, the stator coil assembly 22 cannot be inserted into the slots 21a at a higher density, so output cannot be improved.